DAB vs. Internet Radio Sound Quality

DAB was launched in the UK in 1995 with the promise of a greater choice of stations, a more robust service with less interference and noise and better sound quality. Whilst some of these benefits have been achieved, there have always been concerns about the sound quality on DAB radio, which is often worse than on FM. This leads to the question, can you get better sound quality by listening to the radio online? In this article, we’ll attempt to answer that question.

DAB

Digital radio in the UK is currently based on the DAB standard, which uses the old MP2 codec rather than the newer and more efficient MP3 standard or the HE-AAC v2 codec used by DAB+ radio. It is, therefore, based on old technology which doesn’t offer the best sound quality.

The major problem with DAB currently is that there is limited bandwidth available and this has to be shared between an increasing number of stations. To squeeze them all in, radio broadcasts are at a lower rate than is ideal. In other words, to achieve one of digital radio’s benefits of having more choice, sound quality has been sacrificed.

It’s generally accepted that, to achieve a proper ‘high fidelity’ sound quality, broadcasts need to be at least in the 192-256 kbps (kilobits per second) range, with the higher value being necessary for stereo broadcasts and the lower one acceptable for mono. Sadly, very few stations seem to be achieving that level and some broadcast as low as 64 kbps in mono.

BBC Radio 3 is one of the best performers, achieving 160-192 kbps, while most others are in the 80-128 kbps range. Lower bit rates may be acceptable for the more efficient compression achieved by MP3, where 48 kbps is the equivalent of 64 kbps in MP2.

The problem is due to a lack of bandwidth combined with the cost of using that bandwidth. This has encouraged stations to broadcast at lower bit rates and has enabled more stations to be squeezed in. The irony is that this degradation of the service is occurring at a time when TV is constantly improving its picture quality

DAB+

DAB+ was launched in 2007 and has since been adopted as standard in some countries but not in the UK. It uses the improved HE-AAC v2 audio codec, which is also used in iPods.

DAB+ has better error correction that improves the sound and has more efficient compression so that, for example, 48 kbps on DAB+ has the same sound quality as 128 kbps on DAB. This, therefore, enables a better sound quality to be achieved with the same bandwidth.

Both DAB and DAB+ can be broadcast from the same transmitters and the same multiplexing equipment, and most newer DAB radios can receive both DAB and DAB+. Older radios, however, which don’t have the Digital Radio tickmark, can only receive DAB and can’t be upgraded to DAB+. As a consequence, the government is reluctant to switch over fully to DAB+ since this will leave many digital radio owners with no service.

Some local stations are broadcasting in DAB+ but all the national ones and most local ones are still just broadcasting on DAB. It seems unlikely, therefore, that DAB+ will solve the sound quality problem in the foreseeable future. There are apparently plans for a new DAB multiplexer and this could run DAB+ in parallel, although bandwidth and cost may again be limiting factors.

Internet Radio

Listening to the radio over the internet can provide improved sound quality when compared to DAB. Several stations use the more efficient AAC codec and some of them broadcast at 256 kbps or above to achieve superior sound quality when broadcasting online.

The BBC now has high quality 320 kbps streams for all its national stations (see below) while BBC Radio 3 recently launched a pilot to deliver lossless compression over the internet. This uses FLAC compression, MPEG DASH, HTML5 and Media Source Extensions to provide a claimed original sound quality. It’s available to Firefox and Chrome users and is only a pilot but may influence future developments.

Whilst it offers some hope and provides access to over 20,000 stations, internet radio isn’t always an ideal solution. It requires a stable broadband connection and can incur data usage charges depending on your contract.

Listening to internet radio in the car can be problematic since it relies on your phone provider’s network and you’ll often experience breaks in the service as you move.

320 Kbps BBC Radio Streams

Here are links to where you can stream BBC radio in 320 kbps. You can listen to them in the Safari web browser or with VLC media player.

Conclusion

To conclude, the the highest quality internet radio streams offer better sound quality than DAB radio. Most DAB radio stations broadcast at 128 kbps, whereas online radio can be as high quality as 320 kbps. However, the bitrate of DAB radio broadcasts and internet radio streams can vary greatly, so the above figures are just a general guide.

Of course, you’ll only be able to appreciate the higher audio quality of an internet radio stream if you have good audio equipment: high-quality speakers, headphones or a standalone internet radio.

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